1. Field
The following description relates generally to wireless communications, and more particularly to providing synchronization between base stations via signals sent over a low reuse channel in a wireless communication environment.
2. Background
Wireless communication systems are widely deployed to provide various types of communication content such as, for example, voice, data, and so on. Typical wireless communication systems can be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, . . . ). Examples of such multiple-access systems can include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and the like. Additionally, the systems can conform to specifications such as third generation partnership project (3GPP), 3GPP long term evolution (LTE), ultra mobile broadband (UMB), and/or multi-carrier wireless specifications such as evolution data optimized (EV-DO), one or more revisions thereof, etc.
Generally, wireless multiple-access communication systems can simultaneously support communication for multiple mobile devices. Each mobile device can communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to mobile devices, and the reverse link (or uplink) refers to the communication link from mobile devices to base stations. Further, communications between mobile devices and base stations can be established via single-input single-output (SISO) systems, multiple-input single-output (MISO) systems, multiple-input multiple-output (MIMO) systems, and so forth. In addition, mobile devices can communicate with other mobile devices (and/or base stations with other base stations) in peer-to-peer wireless network configurations.
Heterogeneous wireless communication systems commonly can include various types of base stations, each of which can be associated with differing cell sizes. For instance, macro cell base stations typically leverage antenna(s) installed on masts, rooftops, other existing structures, or the like. Further, macro cell base stations oftentimes have power outputs on the order of tens of watts, and can provide coverage for large areas. The femto cell base station is another class of base station that has recently emerged. Femto cell base stations are commonly designed for residential or small business environments, and can provide wireless coverage to mobile devices using a wireless technology (e.g., 3GPP Universal Mobile Telecommunications System (UMTS) or Long Term Evolution (LTE), 1×Evolution-Data Optimized (1×EV-DO), . . . ) to communicate with the mobile devices and an existing broadband Internet connection (e.g., digital subscriber line (DSL), cable, . . . ) for backhaul. A femto cell base station can also be referred to as a Home Node B (HNB), a femto cell, or the like. Examples of other types of base stations include pico cell base stations, micro cell base stations, and so forth.
Base stations in a wireless communication environment oftentimes attempt to operate in a synchronized manner. Synchronization among base stations in a wireless network can be beneficial for mitigating interference between base stations. For instance, if respective clocks of base stations are not aligned in time or frequency, the base stations can interfere with each other, thereby detrimentally impacting performance. Additionally, synchronization between base stations can enable employing virtual multiple-input multiple-output (MIMO) or sensor data fusion.
Traditionally, synchronization between base stations in a wireless cellular network can be achieved by collocating a respective Global Positioning System (GPS) receiver at each base station. A GPS receiver can provide a timing source for a base station. Accordingly, a clock of a base station can be aligned utilizing information obtained via a GPS receiver. Thus, synchronization between the base stations can be achieved since each base station can align its corresponding clock by employing information received by a respective GPS receiver.
GPS receivers and/or GPS signals, however, can be unavailable for synchronization purposes under various scenarios. For example, lack of availability of GPS receivers and/or GPS signals can be due to manufacturing cost considerations, power consumption limitations, and/or lack of line-of-sight to GPS satellites; however, it is to be appreciated that GPS receivers and/or GPS signals can be unavailable due to any other reason(s). For instance, less powerful base stations (e.g. femto cell base stations, pico cell base stations, . . . ) can be included in a heterogeneous wireless communication system along with macro cell base stations. The less powerful base stations can be leveraged to enhance network throughput; yet, these less powerful base stations oftentimes can be placed indoors (e.g., fail to receive GPS signals from GPS satellites, . . . ) and/or lack GPS receivers associated therewith.